Net Loss Per Share Available to Common Stockholders - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Earnings Per Share [Abstract]
Loss allocated to convertible preferred stockholders	$ 0us-gaap_TemporaryEquityNetIncome

The portion of net income or loss attributable to temporary equity interest.

No definition available.

Name:	us-gaap_TemporaryEquityNetIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration